The association of psychosocial factors--stress, personality or social factors-- and cancer incidence, prognosis or mortality has been proposed and argued about. The possibility of such an association continues to be examined. A prospective study on the Western Collaborative Study Group (WCGS) relating Type A and Type B behavior patterns to later cancer mortality is being pursued. Preliminary results of a l7-year follow-up show nonsignificant age-adjusted relative odds of l.32 in favor of Type A persons being at greater risk than Type B, thus maintaining a similar positive but nosignificant finding for the l0-year follow-up carried out earlier. Epidemiologic data from other sources are being examined and a theoretical position is being developed in regard to stress, personality and their relationship to etiology and prognosis of cancer in humans.